danryan.us

Q121. Consider a "leaky" reservoir. Current volume 1,200 million gallons. Inflow 200 million gallons per month. Consumption 150 million gallons per month. Leakage 5% of current volume per month.

1. Draw a stock and flow diagram of the situation.
2. Draw a causal loop diagram showing the relationship between reservoir volume and the net in/out flow.
3. Identify amount(s) and rate(s).
4. Write the difference equation in the form $P_{n+1} = a \times P_n + b$.
5. Calculate the expected equilibrium.
6. Set up Excel model.
7. Chart reservoir volume vs. time.